Alignment adapter and alignment design for a connector therefor

ABSTRACT

An adapter with novel alignment features engages alignment features on a plug, providing general alignment of the ferrule holders and ferrules in the plug. After the plug engages the adapter, the ferrule holders engage a second set of alignment features in the adapter to provide fine alignment for the ferrules.

REFERENCE TO RELATED CASE

This application claims priority under 35 U.S.C. § 119 (e) toprovisional application No. 61/789,499 filed on Mar. 15, 2013, thecontents of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

There is a need for fiber optic connectors with fiber optic ferrulesthat are ganged together with a tight pitch between those fiber opticferrules. Such a design allows for many fiber optic ferrules to beconnected simultaneously while occupying less space. In addition, itallows the fiber optic ferrules to be organized in a prearranged routingof the optical fibers so that the complexity of fiber optic connectorrouting is reduced for the user. Typically, these ganged fiber opticferrules are mounted into a single housing and the housings are thenmated to one another. The alignment between a pair of ferrules to bemated is complex and requires tight tolerances because there is atolerance stack-up that includes the true position of the fiber opticferrule relative to the housing. By requiring a tight tolerance of thehousing relative to the fiber optic ferrule, the designs are expensiveto design, maintain, and to scale to various fiber optic ferrule counts.It is also difficult to scale to very large arrays of fiber opticferrules within one housing due to the true position tolerance requiredfor every fiber optic ferrule to the housings and also the largerdistances from the fiber optic ferrules to the housings.

An alternative way to align the ferrules to each other is to align theferrule holders to one another through features in the adapter. Ratherthan using the sides of the ferrule holder to align the ferrule holderto the adapter, top and bottom keys on the ferrule holder align theferrule holder relative to the adapter in the x-direction. Theorientation of the ferrule holder is controlled by the width differencebetween the top and the bottom key. The height of the ferrule holderaligns the ferrule holder in the y direction. A plug is used to assemblea plurality of the ferrule holders together. The ferrule holdersprotrude through the plug so the ferrule holder features can be alignedin the adapter after the plug engages the adapter and aligns the ferruleholders with their own structures. The alignment in the X and Ydirections between the ferrule holder and the adapter are maintainedwithin 100 microns, preferably within 50 microns. The ferrule holdersare relatively loosely held within the plug so as to not over constrainthe ferrule holders in the adapter (greater than 100 microns). Thegrooves within the adapter that aligns the ferrule holders is onecontinuous feature for both sides of the adapter and the mating ferruleholders. By making the groove one continuous feature for both sides, thealignment the mating ferrule holders is guaranteed. The size of thegroove is critical but the true position of the alignment featurerelative to the adapter-to-plug alignment feature is not critical. Byusing this alignment mechanism, large arrays of ferrule holders can bemanufactured. Only the size of the alignment mechanism in the ferruleholder and the size of the alignment mechanism in the adapter must bemaintained. The true position tolerances are significantly reduced.

Thus, an adapter and adapter assembly with novel alignment features isprovided to engage with alignment features on a plug, which is turnassists in aligning the ferrule holders with alignment grooves in theadapter.

SUMMARY OF THE INVENTION

The present invention is directed to an adapter for aligning fiber opticferrules inserted from opposing sides that includes a main body havingan opening extending between a first side and a second side, the firstside and the second side separated by a central portion, at least onegroove in a top surface and a bottom surface of the first side and thesecond side, and a plurality of grooves disposed in a top surface andthe bottom surface of the central portion, each of the plurality ofgrooves extending through the central portion from the first side to thesecond side.

According to another aspect of the present invention, adapter assemblyfor aligning one plurality of optical ferrules to another plurality ofoptical ferrules includes an adapter having an opening extending betweena first side and a second side, the adapter having a plurality ofgrooves in the opening and extending in a direction from the first sideto the second side, a plurality of ferrule holders, each of theplurality of ferrule holders having a central opening extending from afirst end to a second end to resiliently retain a fiber optic ferruletherein, each of the plurality of ferrule holders having an opening infirst end and in communication with the central opening, the second endopposite the first end and through which optical fibers extend, each ofthe plurality of ferrule holders having a projection on opposite outsidesurfaces to engage a corresponding groove in the adapter, and a plughaving an outside surface and an inside surface, the inside surfacedefining an opening through the plug to hold a plurality of ferruleholders therein adjacent one another, the plug having grooves in theinside surface to engage the projections from the plurality of ferruleholders to align and orient the ferrule holders in the plug.

In yet another aspect, a ferrule holder includes a main body having acentral opening to resiliently retain a fiber optic ferrule therein, acentral opening in the main body and extending from a first end to asecond end to resiliently retain a fiber optic ferrule therein, thefirst end having an opening therein and in communication with thecentral opening, the second end opposite the first end and through whichoptical fibers extend, and a projection on opposite outside surfaces ofthe main body to engage a corresponding groove in an adapter.

The present invention is also directed to a fiber optic connector thatincludes a plurality of ferrule holders, each of the plurality offerrule holders having a central opening extending from a first end to asecond end to resiliently retain a fiber optic ferrule therein, theferrule holder having an opening in first end in communication with thecentral opening, the second end opposite the first end and through whichoptical fibers extend, each of the plurality of ferrule holders having aprojection on opposite outside surfaces to engage a corresponding groovein the adapter, and a plug having an outside surface and an insidesurface, the inside surface defining an opening through the plug to holda plurality of ferrule holders therein adjacent one another, the plughaving grooves in the inside surface to engage the projections from theplurality of ferrule holders to align and orient the ferrule holders inthe plug

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description of the present embodiments of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated into and constitutea part of this specification. The drawings illustrate variousembodiments of the invention and, together with the description, serveto explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of an adapter assemblyaccording to the present invention;

FIG. 2 is an exploded view of the adapter assembly of FIG. 1;

FIG. 3 is a perspective view of a cut-away view of the adapter of FIG.1;

FIG. 4 is a front elevational view of the adapter of FIG. 1;

FIG. 5A is a top perspective view of one embodiment of a ferrule holderand ferrule that can be used in the adapter assembly of FIG. 1;

FIG. 5B is a bottom perspective view of the ferrule holder and ferruleof FIG. 5 a;

FIG. 5C is a front view of the ferrule holder and ferrule of FIG. 5 a;

FIG. 6A is a top perspective view of a plug and ferrule holdersaccording to the present invention;

FIG. 6B is a bottom perspective view of the plug and ferrule holders ofFIG. 6A;

FIG. 6C is a front elevational view of the plug and ferrule holders ofFIG. 6A;

FIG. 7A is a partial cross sectional view of a portion of a ferruleholder of FIG. 5;

FIG. 7B is a partial cross sectional view of a portion of the centerportion of the adapter;

FIG. 8 is a cross sectional view of the adapter assembly in the centerof the adapter assembly; and

FIG. 9 is a cross sectional view of the adapter assembly through aferrule holder and ferrule.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiment(s) of the invention, examples of which are illustrated in theaccompanying drawings. Whenever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

Referring to FIGS. 1 and 2, one embodiment of an adapter assembly 10 isillustrated. The adapter assembly 10 includes an adapter 100, a plug 200and a ferrule holder 300. The adapter assembly 10 is used to alignferrules 12 to other ferrules in a tightly controlled manner and in atighter space than has been possible before. The ferrules 12 aretypically multi-fiber ferrules, particularly MT type ferrules, but thepresent invention may include other types of ferrules. The ferrules 12are disposed within the ferrule holder 300 and have optical fibers 14secured therein, which may be loose optical fibers, ribbonized opticalfibers, or optical fibers in any other configuration. The ferrules 12are resiliently held in the ferrule holders 300 using a spring push 16that engages a spring 18. The spring 18 then presses on a pin keeper 20,as is known in the art, to bias the ferrules 12 forward in the ferruleholder 300. As is described in more detail below, the ferrules 12 areheld somewhat loosely within the ferrule holder 300 so that they canmove relative to the ferrule holder 300 to align with other ferrules 12that are inserted in the adapter 100 from the other side. Similarly, theferrule holders 300 are inserted into the plug 200 and they are alsoloosely held in the plug 200. That is, there is typically more than 100microns of movement in the x and y directions (See FIG. 4.) available tothe ferrule holder 300 in the plug 200, as explained in more detailbelow.

As illustrated in FIGS. 5A-C, the ferrule holder 300 has a main body 302with a central opening 304 that extends from a first end 306 to a secondend 308 to house the fiber optic ferrules 12. The first end 306 has anopening 310 therein to allow access to the ferrule 12. The ferrule 12may or may not exit the main body 302. That is, the ferrule 12 mayextend beyond the main body 302 as shown in the figures or it may beflush with the first end 306, second end 308 allows for the opticalfibers 14 (shown in FIGS. 5A and 5B to have a boot and a covering) toexit the ferrule holder 300. The ferrule holder 300 has a top surface312 and a bottom surface 314, with a cantilevered latch 316 to engagethe plug 200. The top surface 312 has a projection 320 and the bottomsurface 314 has a projection 322. The projections 320,322 are preferablyelongated and have a chamfered front end. The projections 320,322 areused to engage grooves in the plug 200 and the adapter 100 to positionthe ferrule holders 300 with precision in the adapter 100. Theprojection 320 has a width that is different that the width ofprojection 322 so as to act as a key in inserting the ferrule holder 300in the plug 200. While the projection 320 is wider than projection 322,it could be opposite in that projection 320 is more narrow thanprojection 322. The projections 320,322 are preferably on the top andthe bottom surfaces 312,314 of the ferrule holder 300 to allow, asillustrated below, more ferrule holders to be inserted into the adapter100 and the plug 200. The projections 320,322 are used to position theferrules 12 in the adapter in the x and y directions, eliminating theneed for side walls to position the ferrule holders 300 and the ferrules12.

The plug 200 will now be described relative to FIGS. 6A-6C. The plug 200has an outside surface 202 and an inside surface 204. The inside surface204 defines an opening 206 therethrough to allow the ferrule holders 300to be inserted therein. The inside surface 204 has a plurality ofgrooves 208 on a top side 210 and a corresponding plurality of grooves212 on the bottom side 214. The grooves 208 and 212 are dimensioned toaccept the projections 320,322 from the ferrule holders 300. It shouldbe noted that the ferrule holders 300 are adjacent to one another, thatis side-by-side without any material from the plug 200 therebetween.Applicant means that by using the term adjacent herein, there is nostructure that comes between the neighboring ferrule holders 300.

The outside surface 202 also has a projection 220 on the top of the plug200, seen in FIG. 6A, and also a projection 222 on the bottom of theplug 200, seen in FIG. 6B. Again, as with the projections 320,322,projection 220 has a width that is different that the width ofprojection 222 so as to act as a key in inserting the plug 200 into theadapter 100. While the projection 220 is narrower than projection 222,it could be opposite in that projection 220 is wider than projection222.

The plug 200 also has two cantilevered latches 230 on the sides toengage corresponding structure on the adapter 100. There are also latchreceptacles 232 on the top side of the plug 200 to engage the latches316 of the ferrule holders 300.

As noted above, the grooves 208 and 212 in plug 200 are dimensioned toaccept the projections 320,322 from the ferrule holders 300. There issufficient movement in the ferrule holders 300 relative to the plug 200that when the plug 200 and ferrule holders 300 as assembled is insertedinto the adapter 100, that the ferrule holders 300 can move to allow theprojections 320,322 from the ferrule holders 300 to engage correspondinggrooves in the adapter 100 as described below in more detail.

Returning to FIGS. 3 and 4, the adapter 100 is illustrated in moredetail. The adapter 100 has a main body 102 with an opening 104extending between a first side 106 and a second side 108. The first side106 and a second side 108 are separated by a central portion 110. Thefirst side 106 has a top surface 112 and a bottom surface 114. The topsurface 112 has a groove 116 and the bottom surface 114 has a groove118. The grooves 116,118 correspond to the projections 220,222 from theplug 200. The location of the wider groove in the adapter 100 willcorrespond with the wider projection on the plug 200.

The adapter has the center portion 110. Center portion 110 preferablyhas a wall 130 that extends across the opening 104 in the adapter 100and divides the center portion 110 in half. The center portion 110 alsohas a raised bottom portion 132 and a dropped top portion 134 thatnarrows the opening 104 in the center portion 110. The wall 130preferably extends from the raised bottom portion 132 and a dropped topportion 134 or it may be excluded completely if there is no EMI concernswith the adapter 100. The wall 130 has a plurality of openings 136 thatare sized to allow the ferrules 12 to pass therethrough to engage acorresponding ferrule 12. As noted above, if the ferrules 12 only extendto the end of the ferrule holder 330, then the openings 136 should besized to allow the ferrule holders to also extend therethrough. Theadapter 100 may also have an elastomeric gasket 150 that encircles anexternal surface of the adapter 100 to provide EMI shielding.

The raised bottom portion 132 and a dropped top portion 134 also have aplurality of grooves 140, 142, respectively, that extend completelyacross the central portion 110. The grooves 140, 142 are like those inthe plug 200, in that they are to engage the projections 320,322 fromthe ferrule holders 300. The grooves 140,142 preferably extendcompletely across the center portion 110 as they are formed with thesame insert in the mold. Therefore, the grooves 140,142 are sure toalign the ferrule holders 300 on each side of the adapter 100 as theyare inserted into the adapter 100.

As the plug 200 with the ferrule holders 300 positioned therein areinserted into the adapter 100, the projections 220,222 from the plug 200engage the grooves 116,118 on the top surface 112 and the bottom surface114 to roughly align the ferrule holders 300 with the center portion 110and the plurality of grooves 140 in particular. Then, as the plug 200 isinserted farther into the adapter 100, the projections 320,322 from theferrule holders 300 engage plurality of grooves 140, 142 to align theferrule holders 300 with the adapter and the openings 136 in the wall130. When a plug 200 is inserted on the second side, the ferrules in theferrule holders on the other side will be in alignment with the firstside.

The position of the ferrule holders 300 on the first side 106 of theadapter relative to the ferrule holders 300 on the second side 108 iswhat allows the optical ferrules to be aligned with one another. Thereis no need, as discussed above, to worry about the stacking oftolerances as in the prior art. The positioning of the projections320,322 on the ferrule holders 300 relative to the plurality of grooves140, 142 is important. With reference to FIGS. 7A and 7B, theprojections 320,322 are used to control the x and y locations of theferrule holders 300. The surfaces 340 of the projections 320,322 (FIG.7A) align with the surfaces 150 in the adapter (FIG. 7B) to control thex direction of the ferrule holder 300 relative to the adapter 100. Thesurfaces 352 of the ferrule holder 300 align with the surfaces 152 ofthe raised bottom portion 132 and the dropped top portion 134 of thecenter portion 110 to control the y direction of the ferrule holder 300relative to the adapter 100. The surfaces of the projections 320,322could also align in the y direction, given that they are parallel to thesurfaces 352.

A cross section of the adapter assembly 10 is illustrated in FIG. 8through the center of the adapter assembly. This illustrates theprojections 220,200 in the openings 116,118 of the adapter 100. FIG. 9is a cross sectional view of the adapter assembly 10 through a ferruleholder and ferrule illustrating the engagement of the projections320,322 in the openings 140, 142.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

We claim:
 1. An adapter for aligning fiber optic ferrules inserted fromopposing sides comprising: a main body having an opening extendingbetween a first side and a second side, the first side and the secondside separated by a central portion; at least one groove in a topsurface and a bottom surface of the first side and the second side ofthe main body; and a plurality of grooves disposed in a top surface andthe bottom surface of the central portion, each of the plurality ofgrooves extending through the central portion from the first side to thesecond side.
 2. The adapter according to claim 1, further comprising awall disposed within and across the central portion of the main body andbetween the first side and the second side, the wall having at least onepassage therein to allow at least a portion of the fiber optic ferrulesinserted from the first and second sides to pass therethrough.
 3. Theadapter according to claim 2, wherein the at least one passage comprisesa plurality of passages, the plurality of passages corresponding to thenumber of fiber optic ferrules.
 4. The adapter according to claim 1,wherein the opening in the central portion of the main body is smallerthan the opening in the first and second sides.
 5. The adapter accordingto claim 1, further comprising a conductive elastomeric gasketencircling an external surface of the adapter to provide EMI shieldingto the adapter.
 6. The adapter according to claim 1, wherein the firstand second sides are configured to receive a plurality of opticalferrules.
 7. The adapter according to claim 1, wherein the plurality ofgrooves in the top surface of the central portion have a first width andthe plurality of grooves in the bottom surface of the central portionhave a second width, and the first and second widths are different. 8.The adapter according to claim 1, wherein the at least one groovecomprises a first groove in the top surface and a second groove in thebottom surface.
 9. The adapter according to claim 8, wherein the firstgroove has a first width and the second groove has a second width, thefirst and second widths being different.
 10. The adapter according toclaim 9, wherein the first and second grooves act as a key way for aplug.
 11. The adapter according to claim 3, wherein the plurality ofpassages are sized to allow a ferrule holder to enter therein.